Of the 109 homeless people who should be registered in those categories, 76 are in compliance with state law, officials said.

"There's no office in the state to keep track of them," said Cara Smith, policy director for the Illinois attorney general's office.

It wasn't until Harvard police picked up Austin for hitchhiking at 2 a.m. Oct. 5 that anyone realized he hadn't registered as a child murderer, authorities said. The law requires such criminals to register within five days of their release from prison.

After that, the ones who are homeless must check in every week with police, officials said.

Austin and his wife, who lived in Winthrop Harbor, had been going through a divorce when their 7-year-old daughter, Kristin, disappeared on Oct. 4, 1990. Later that month, police charged Austin with her murder.

Admitting his guilt but saying he was mentally ill, Austin was sentenced in 1991 for killing the child and burying her in a Michigan field.

He was paroled in March 2005 but was sent back to prison when his parole officer couldn't locate him, said Illinois Department of Corrections spokesman Derek Schnapp.

Austin finished his sentence and was released on Sept. 14. His discharge papers indicated he was homeless and would be living in Waukegan, officials said.

Prison officials notified the Lake County state's attorney and sheriff, as well as the Waukegan and state police, Schnapp said.

There was little the prison system could do to keep track of him, Schnapp said.

"He's no longer in our jurisdiction," Schnapp said. "He's on his own."

The attorney general's office is trying to work out the best way to keep tabs on homeless criminals who are required to register, Smith said.

On Tuesday, Austin quietly answered "yes" to questions about whether he understood the three charges against him. He was charged with failing to register as a child murderer, which could send him back to prison for five years; obstructing justice; and hitchhiking, a misdemeanor that carries a fine of up to $2,500.

The hitchhiking in Harvard caused his latest scrape with police, prosecutors said. "It was an odd time to be hitchhiking through town," said McHenry County First Assistant State's Atty. Tom Carroll. "And then there was an issue of he wouldn't identify himself."

An investigation determined that Austin had recently been released from prison and that he hadn't registered as a child murderer, Carroll said.

Jed Stone, the lawyer who represented Austin in 1991, said his former client has served his time and wasn't a threat to children. Instead of jailing him again for not registering as a child murderer, Stone said the state should find ways to help people like Austin cope.

"When people get released from prison, they get released without a lot of help, a whole lot of backup, a whole lot of support structure," Stone said.